Carboxylate-containing photocatalytic body, manufacture and use thereof

ABSTRACT

Supported photooxidation catalysts containing a metal oxide or metal ion as catalyst which is fixed to the support by means of carboxylate moieties are an alternative to existing such catalysts, particularly if low cost supports such as organic polymers, particularly polyethylene, are used. The supported photocatalysts can be used in mineralisation of organic pollutants in both liquids and gases and show reduced leaching of the catalyst and good resistance towards reactive oxygen species generated during the degradation process.

FIELD OF THE INVENTION

Industrial organic compounds such as chlorophenols, azo dyes, etc. arewidely distributed in soils and waters. Chlorophenols are listed ashighly toxic pollutants by governmental agencies. Azo-dyes do notundergo bacterial degradation in waste-water treatment plants due to thepresence of aromatic and sulpho-aromatic groups. Oxidativephotocatalytic reactions with suitable photocatalysts such as titaniumdioxide and photo-Fenton processes with e.g. Fe³⁺ ions are able to breakdown such molecules totally or partially so that cheaper biologicalprocess can be used as a second stage to achieve completemineralisation. The present invention relates to the field ofphotocatalytic oxidative degradation of such organic pollutants fromwastewaters, effluents and vent gases. Particularly it relates to thephotocatalytic degradation of pollutants in wastewaters and effluentswhich are not easily mineralizable by mere biological (i.e. bacterial)degradation processes.

PRIOR ART

The literature dealing with photocatalytic degradation of suchpollutants is abundant. In the prior art photocatalysts were oftenapplied as suspensions, but costly problems associated with catalystleaching, settling, flocculation and the need for eventual catalystseparation by filtration during post treatment, hindered their widescale application in industry. In systems using photo-Fenton typephotocatalytic degradation, removal of Fe ions after treatment isexpensive. Therefore, catalyst immobilisation related research hasattracted wide attention (see e.g. J. Fernandez, J. Bandara, A. Lopez,P. Albers and J. Kiwi, J. Chem. Soc. Chem. Commun. 1998, 1493). Simplecoating of the catalyst over glass, ceramics and polymers often lead tocatalyst leaching and dissolution (U. Stafford, K. A. Gray and P. V.Kamat, J. Phys. Chem, 1994, 98, 6343; H. Al-Ekabi and N. Serpone, J.Phys. Chem., 1988, 92, 5726). There are reports on buoyant TiO₂-coatedglass micro-bubbles (J. Schwitzgebel, J. G. Ekerdt, H. Gerischer and A.Heller, J. Phys. Chem., 1995, 99, 5633) and polystyrene beads made bythermal treatment (M. E. Fabiyi and R. L. Skelton, J. Photochem.Photobiol. A: Chem, 2000, 132, 121). Immobilized catalysts may showreduced activity which depends much on the materials and proceduresadopted. Another problem generally noticed is the chemical attack by OHradicals on the polymer substrates (B. Ranby and J. F. Rabeck in‘Photodegradation, Photo-oxidation and Photostabilization of Polymers’,J. Wiley & Sons, London, 1975, p-290). Photocatalysts immobilized onexpensive Nafion films (J. Fernandez, J. Bandara, A. Lopez, P. Albersand J. Kiwi, J. Chem. Soc. Chem. Commun. 1998, 1493) are noteconomically viable, since many industries can not afford highinvestments for waste water treatment plants.

In example 2 of EP-A-0 846 494 an acrylic resin plate and a methacrylicresin plate are treated with 2% sodium hydroxide solution at 80° C. for30 minutes, washed and dried, then the plates are coated with titaniumperoxide sol by dipping. In examples 3 and 4 a water absorbing tile anda float glass, coated with glass beads, are coated with a 50:1 mixtureof titanium peroxide sol and titanium dioxide. No indications are givenas to the nature of the fixation of the titanium to the surface of thesephotocatalytic bodies. The description states that any known proceduresmay be used to apply titanium oxide sol, titanium peroxide sol ormixtures therefrom ono the substrate, such as dipping, spraying andcoating.

The task underlying the present invention is to find photocatalyticbodies with improved fixation to the carrier substrate, i.e. withreduced catalyst leaching, which however show stable and reproduciblecatalytic behaviour.

SUMMARY OF THE INVENTION

The solution to the above problem is given by the photocatalyticoxidative bodies of claim 1. It has unexpectedly been found that thebonding of photooxidative catalytic metal ions or metal oxides givehighly active, easily utilizable catalytic systems for the degradationof organic pollutants, which do not lose appreciably their activityafter multiple usage. The catalytic bodies exhibit, quite independentlyfrom the type of polymeric carrier used, good resistance to reactiveoxygen species formed during the degradation process.

It is assumed that a significant part of the eventual bonding of thecations of the photooxidation catalyst occurs via carboxylate moieties—COO⁻ present on the surface of the polymeric carrier, although other,unknown mechanisms of bonding might be involved as well, in addition tothis one.

Further objects of the invention are processes for the manufacture ofthe above catalytic bodies and degradation processes for organicpollutants using these catalytic bodies.

DESCRIPTION OF THE FIGURES

FIG. 1 shows the gradual decrease in total organic carbon content (TOC)upon degradation of three different model compounds (FIG. 1 a2-chlorophenol; FIG. 1 b 4-chlorophenol; FIG. 1 c 2,4-dichlorophenol)using: ◯; a TiO₂-coated photocatalytic oxidative sheet of the invention,under illumination; ★: a suspension of TiO₂ (75 mg/L) underillumination; and ●: a TiO₂-coated photooxidative catalytic film of theinvention, in the dark. The inset in FIG. 1 b shows the absorptionspectra of a) a polymer film without TiO₂ coating, b) after coating withTiO₂, and c) the TiO₂-coated film after six runs in catalyticdegradation.

FIG. 2 a shows the gradual decrease in total organic carbon content(TOC) upon photocatalytic oxidative degradation of 4-chlorophenol usinga): a Fe₂O₃-coated photocatalytic oxidative sheet according to theinvention in presence of 0.01 M H₂O₂, under illumination; b): same asa), but in the dark; c): using a Fe₂O₃ suspension (25 mg/L) in presenceof 0.001 M H₂O₂, under illumination; d): same as c), but with 75 mg/Lsuspension; e): same as c), but in presence of 0.01 M H₂O₂, f): same asc), but with 75 mg/L suspension and in presence of 0.01 M H₂O₂.

FIG. 2 b shows the gradual decrease in total organic carbon content(TOC) upon photocatalytic oxidative degradation of the azo dye OrangeII, whereby the conditions in a) to f) are the same as in a) to f) ofFIG. 2 a, respectively.

FIG. 3 a shows the gradual decrease in total organic carbon content(TOC) upon photo-Fenton degradation of 4-chlorophenol using aFe³⁺-coated photooxidative catalytic sheet according to the invention inpresence of 0.01 M H₂O₂, ◯: under illumination; and ●: in the dark.

FIG. 3 b shows the gradual decrease in total organic carbon content(TOC) upon photo-Fenton degradation of the azo dye orange II, withconditions and symbol meanings as in FIG. 3 a.

DESCRIPTION OF THE INVENTION

The catalytic body according to the invention may have the shape ofbeads, pellets, granules, sheets, membranes or any other shape whichpreferably has a high surface to volume ratio, in order to facilitatethe oxidation process of the invention which is a heterogeneous process.

The metal cation containing photooxidative catalysts used in the presentinvention are known per se from the field of photodegradation of organicpollutants. Examples thereof are metal oxides containing metal cationssuch as TiO₂ (Ti⁴⁺ containing), Fe₂O₃ (Fe³⁺ containing), ZnO (Zn²⁺containing), SrTiO₃, BaTiO₃ (Ti⁴⁺ containing), In₂O₃ (In³⁺ containing),Ta₂O₅ (Ta⁵⁺ containing) WO₃ (W⁶⁺ containing), Cu₂O (Cu⁺ containing) andRuO₂ (Ru⁴⁺ containing), and mixed oxides therefrom. Here, TiO₂, Fe₂O₃and the mixtures therefrom are preferred according to the invention.

In cases where in the degradation reaction H₂O₂ is required more, andparticularly when this should be generated in situ from O₂, the oxideZnO is preferred. Production of excess H₂O₂ with ZnO as the catalyst maybe further enhanced by co-attaching with the ZnO a small amount ofcerium oxide, e.g. 0.001 to 1% by weight, based on the ZnO, to thesurface of the polymeric carrier. For this the desired amount of ceriumoxide or hydroxide may be added to the ZnO suspension in the bondingreaction.

ZnO is also preferred for degradation of alcohols (primary, secondary,tertiary).

The above oxides may be used in doped form, e.g. doped with Li, Al, Nb,Ti, Si, P, In, Ga, Sb, Cr, preferably in amounts of 0.1 to 10 atom %,more preferably 5 atoms. The doping is perferably done prior to bondingof the oxide to the carrier surface, preferably by known techniques suchas metal salt solution impregnation, followed by high temperaturecalcination, milling and re-calcination. Metals such as Pt, Pd, Ag, Nior their oxides may be loaded onto the catalytic metal oxide such asTiO₂ before loading onto the polymer. Again the loading may perferablybe done prior to immobilization to the polymeric carrier.

Examples for the photooxidative catalyst are also bare metal cationsthemselves such as Fe³⁺ and Ru³⁺. Here, Fe³⁺ is preferred.

The oxides may be employed in the form of powders or colloids.

Examples of organic polymeric carriers are organic polymers such aspolyesters, polyethylenes, polypropylenes, polystyrenes, or polyamides,a preferred polymer is polyethylene, and a particularly preferredpolymer is linear low density polyethylene (LLDPE).

Examples of inorganic polymeric carriers are glass and ceramics.

The term “surface carboxylate moiety” shall mean carboxylate groups—COO⁻ that protrude from the surface(s) of the polymeric carrier andwhich exhibit a steric shielding low enough that they can co-ordinate tothe metal cation(s) of the catalyst.

Some polymeric carriers may have such groups already present on anysurface therefrom, when the polymeric carrier itself contains suchgroups; otherwise they may be introduced by

-   -   coating the surfaces of the polymeric carrier with a compound        containing carboxylates, carboxylic acid, carboxylic anhydride        or acyl halogenide moieties;    -   mixing the polymeric carrier with such an above compound;    -   chemical derivatization of the surface(s) of the polymeric        carrier.

If carboxylates are present in the polymeric carrier they may be presentas part of the backbone (e.g. in a polyacrylic acid orpoly(methacrylic)acid) or as terminal groups (e.g. as carboxylateterminals in a diol/diacid polyester). Some of these carboxylate groupswill invariably be present at any formed surface of the polymericcarrier and protrude therefrom, although the surface density of thesecarboxylates (and therefore the achievable surface density of oxidativecatalyst) is expected to vary depending on the type of polymeric carrierthat is chosen.

A versatile way of introducing carboxylate, carboxylic acid, carboxylicanhydride or acyl halogenide moieties onto the surfaces of both organicand inorganic polymeric carriers of any type is the coating of thesurface with a solution of a compound containing such moieties,preferably a polymeric compound, and drying. The solution may be formedwith any solvent which is a solvent for the compound and is inert to thecarboxylate derivative present in the compound, but is a non-solvent forthe polymeric carrier. Particular examples of the solvent here arehydrocarbons such as benzene, toluene and halogenated hydrocarbons. Thecarboxylic acid, carboxylic anhydride or acyl halogenide moietiesprotruding from the surface of the formed coating may be prehydrolysedto form carboxylates, if reaction with photocatalytic cations is to bedone, or they may be used as such, if reaction with photocatalyticoxides is to be done. The above coating technique is useful forproducing a reactor vessel with its walls acting as the polymericcarrier.

Another way of producing the carboxylate-containing organic polymericcarrier is the mixing of any bulk organic polymer which does notnecessarily contain such carboxylates (e.g. a low cost polymer such aspolyethylene, polypropylene or polystyrene) in the molten state or insolution or by coextrusion with a specified amount of acarboxylate-containing or carboxylic acid derivative-containing organicpolymer (see above). The resultant mixed polymer again will invariablyhave at its surface a certain amount of carboxylate or carboxylic acidderivative groups, due to the admixed compound. Here again the compoundmay contain carboxylic acids or reactive esters therefrom such as acylhalogenides or carboxylic anhydrides, in particularly those derived frommaleic anhydride or maleic acid which may be pre-hydrolyzed tocarboxylates.

“Surface carboxylate moieties” in the above meaning may also beintroduced onto the surface(s) of a polymeric carrier which per se wouldbe essentially or fully devoid of such moieties, by an appropiatesurface treatment taking into consideration the nature of the polymericcarrier. Examples of such treatments would be the oxidation of surfacearyl methyl groups present to corresponding surface aryl carboxylates byKMnO₄ or acid hydrolysis of surface nitrile groups (e.g. present fromacrylonitrile precursors in the polymeric backbone such as inacrylonitrile/butadiene/styrene copolymer) to surface carboxylates.

Carboxylate groups are introducible into an organic polymeric carrier(both into the bulk or onto its surface) by a process commonly known inthe art as “grafting”. In this process sites of an existing polymerbackbone which are susceptible to free radical hydrogen abstraction ordeprotonation are linked to an α,β-unsaturated carboxylic acid,carboxylate ester, carboxylic anhydride or acyl halogenide. Thesusceptible position is thus added by free-radical or ionic pathway tothe double bond of the unsaturated carboxyl compound which becomessaturated in the process. Such positions on the backbone are e.g.tertiary carbon atoms or carbon atoms which are in α position to anelectron-with-drawing group. The result of the grafting is thus asaturated carboxylic acid derivative which is bound to the polymerbackbone via a C—C bond connecting the susceptible position of thepolymer backbone and the β-carbon atom of the carboxylic acidderivative; e.g. employing maleic anhydride in the grafting processgives in the finished product grafted succinic anhydride, using acrylategives grafted propionate, etc. Grafting is possible with many types ofpolymers, such as polyethylene, polypropylene, ethylene vinyl acetate,polystyrene, etc.

Examples of commercially available grafted polymericcarboxylate-containing compounds are the products marketed under thetradenames of Fusabond®, Bynel® and Surlyn®. In these products,manufactured by E.I. Dupont de Nemours & Company, maleic anhydride(Fusabond®, Bynel®) or methacrylate (Surlyn®) is grafted to polymericbackbones such as polyethylene or ethylene vinyl acetate. The contentsof maleic anhydride in Fusabond is about 0.1 to about 1 percent byweight, depending on the type of Fusabond. Reference is also made to theProduct Information Sheets of Dupont in which the different types ofFusabond, Bynel and Sarlyn polymers are further explained. Theapplicants also were able to obtain, at request, from the Geneva branchof Dupont a maleic anhydride-derivatized polyethylene (Fusabond series)which was very similar to the Dupont Bynel commercial product whichcontained about 1,5 percent by weight of grafted maleic anhydride. Theusual application of these commercial products, according to the ProductInformation Sheets of Dupont, is not the use in photooxidation catalysisbut the coupling with mineral fillers such as magnesium hydroxide orglass fibres, when mixing such fillers with polymers; or thecompatibilisation of low-polarity polymers such as polypropylene withhigh-polarity polymers such as polyamide; or the impact modification ofthermoplastic resins.

Carboxylate moieties are inroducible into inorganic polymeric supportssuch as glass or ceramics by silanizing reagents which containcarboxylic acids, carboxylates, carboxylic anhydrides or acylhalogenides. These inorganic carriers contain surface hydroxyls (e.g.AlOH, SiOH) which react with the silanizing reagent. These silanizingreagents may have the following general structure:X—Si(Me)₂—R—COYwherein X denotes a hydroxyl reactive group such as Cl, R denotes thespacer and COY denotes the respective carboxylate derivative. Thesesilanizing reagents can be reacted with the glass or ceramics surfacehydroxyls according to known procedures in the presence of a base. Thesilanizing reagents themselves are accessible by the Speyer reactionbetween chlorodimethylsilane ClSi(Me)₂H and olefins (which in thepresent case contain the spacer and the carboxylate derivative COY) withhexachloroplatinic acid as catalyst.

Particularly preferred is the use of a carboxylic acid grafted orcarboxylic anhydride grafted polymer, particularly a maleicanhydride-grafted linear low density polyethylene (LLDPE) as polymericcarrier.

The polymeric carrier may be initially present in a bulk form such as acommercially available granulate. This may be shaped, if necessary, tothe desired shape such as pellets, sheets, membranes, etc. by knownprocedures of plastics treatment and forming. If the bulk polymer per seis devoid of surface carboxylates of carboxylic acid derivatives and hadto be formed into the shape of interest, then any modification of thesurface which introduces such carboxylates or carboxylic acidderivatives should be done after this forming.

The bonding of the photooxidative catalyst to the surface of thepolymeric carrier may be performed by any of the following types ofreactions:

-   a) For photooxidative catalysts in the form of metal oxides:    Reaction of surface carboxylic acid, surface carboxylic anhydrides    or acyl halogenides moieties with the metal oxide, preferably under    heating and optionally under removal of condensation water; this    reaction works because metal oxides invariably contain hydroxylic    groups at their surface which react with the above moieties.-   b) For photooxidative catalysts in the form of free metal ions:    Reaction of surface carboxylates —COO⁻ with the catalyst metal ions    by contacting of a solution of the metal ion with the surface or by    ion-exchange. The surface carboxylates may be pre-formed by alkaline    hydrolysis of any carboxylic acid derivative (carboxylic acid,    carboxylic ester, carboxylic anhydride or acyl halogenide) on the    surface.

In the case of the photocatalytic metal oxides the reaction mixture willbe a suspension of the oxide, besides the polymeric carrier, in somesolvent. It may then be advantageous to use some high efficiency form ofmixing such as sonication or vibromixing in order to allow more intimatecontacting between the carrier surface and the oxide. Sonication,optionally with application of vacuum, is also advanageous in order toremove gas trapped in the cavities of the metal oxide which also helpsin facilitating contact between the oxide and the carrier surface.

In any case the speed of the bonding reaction may be accelerated byheating the reaction system above the ambient temperature, e.g. to 50 to80° C., preferably to about 75° C.

Optionally a preferably non-ionic surfactant may be used, in order toimprove the wettening of the heterogeneous surfaces when using aqueoussolvents.

The choice of solvent will depend on the bonding reaction to beeffected. In general an aqueous solvent may be used; for the cases wherea carboxylic anhydride or acyl halogenide is to be reacted with asurface hydroxyl-containing photocatalytic metal oxide an organic,essentially or fully water-free solvent such as an ether may also beused.

The loading of the surface of the polymeric carrier with photooxidativecatalyst is governed primarily by the amount of available surfacecarboxylates present on the surface, when the reaction is allowed to goessentially to completion. This may be achieved by using large excessesof the photooxidative catalyst over the amount of available surfacecarboxyls. The amount of surface carboxyls in a given polymeric carriermay be determined by acid-base titration of an aliquot of the polymericcarrier or by ion exchange capacity measurement of such an aliquot andrelating this to the specific surface of the carrier, as determined bye.g. BET measurements. An essentially complete reaction, but with noextra layers of non-bound catalyst on the surface, is preferredaccording to the invention. For this the above unreacted excess of thephotooxidative catalyst is conveniently removed after the reaction bywashing.

The term “environment of use” shall mean empty space which is to befilled with the medium to be decontaminated from organic pollutants bythe catalytic process of the invention. This medium may be any liquid(particularly aqueous) or gaseous mixture containing such pollutants.

The degradation process according to the invention may run analogouslyto the known such processes, but using a photooxidative catalytic bodyaccording to the invention. In the cases of liquid or gaseous media theprocess may be a photooxidation in presence of molecular oxygen (e.g. inthe case of TiO₂-containing catalytic bodies) or in liquid media it mayalso be a photo-Fenton type oxidation (e.g. with Fe³⁺ containingcatalytic bodies), whereby as usual some hydrogen peroxide is used. Thehydrogen peroxide may here be used in an excess over the amount ofpollutants to be degraded, preferably in at least twice the molarconcentration of the sum of the pollutants, more preferably in at leastten times the concentration of the pollutants. Typically the hydrogenperoxide concentration may lie in the range of 0.001 to 0.05 M.

The amount of photooxidative catalytic body is not critical, asdecreasing the amount merely slows down the degradation process. In thecase of chlorophenols as pollutants in aqueous solutions in an initialconcentration of 0.5 mM it was found that an essentially completemineralization is obtained within about 10 hours (see examples for exactconditions).

The type of light source used may be one with an appreciable amount ofnear UV radiation, such as a low, medium or high pressure mercury arclamp; the spectral intensity distribution and the wavelenght of theintensity maximum should preferably be adapted to the absorptionspectrum of the photooxidation catalyst. The relations between type ofphotooxidation catalyst and nature of the light source are known fromconventional photooxidative catalytic bodies.

The degradation process may be run in any vessel or reactor which isessentially transparent to the light to be used.

Particular examples of such organic, not easily mineralizable pollutantswhich can be degraded by the catalyst-containing articles and theoxidation process of the present invention are:

aliphatic primary, secondary and tertiary alcohols or glycols, such asmethanol, ethanol, 2-propanol, tertiary butanol, ethylene glycol,propylene glycol,

halogenated aliphatics such as methyl chloride, ethyl chloride,1,1,1-trichloroethane, 1,2-dichloroethane, chloroform,1,1,2,2-tetrachloroethylene, 1,1,1-trichloroacetaldehyde,1,1,1-trichloroacetic acid, vinyl chloride and halogenated ketones;

aromatics such as benzene, naphthalene, alkylbenzenes (toluene, xylene),styrene, phenols, cresols, aromatic azo compounds (in particularly azodyes such as those used in textile dyeing), anilines, pyridines,quinolines, thiophenes, aromatic sulfonic acids (benzenesulfonic acid,toluenesulfonic acid) and di- and triazines;halogenated aromatics such as mono-, di, tri-, and polychlorinatedbenzenes, naphthalenes, phenols and aryl ethers, examples beingchlorobenzene, 1,2-, 1,3- and 1,4-dichlorobenzene, 2-chlorophenol,4-chlorophenol, pentachlorophenol and tetrachlorodibenzodioxine;organic phosphorus compounds such as phosphoric acid or thiophosphoricacid esters (particularly those used in agriculture as pesticides).

The best embodiment of the catalytic body of the invention, i.e.titanium oxide photooxidation catalyst bound to a maleicanhydride-grafted LLDPE, shows surprising resistivity towards thereactive oxygen species formed during the photodegradation process. Italso is a very cheap alternative to the known carrier-supportedphotocatalytic bodies. The catalytic bodies according to the inventiondo not show significant decrease in activity after several catalyticruns.

The invention will be further illustrated by the following examples.These should not be construed as limits of the scope of the invention.

In the examples percents refer to weight.

EXAMPLES Example 1 Preparation of a Photocatalytic Oxidative TiO₂-CoatedSheet

A sheet of linear low density polyethylene (LLDPE) of 30 μm thickness,grafted with 1.5% of maleic anhydride, namely Fusabond 414 of Dupont,was taken as the polymeric carrier. The sheet was washed with water andthen immersed in an aqueous suspension of TiO₂ (Degussa P25) containing5 g oxide per liter of suspension. The suspension had been sonicatedprior to use for 30 min. The suspension with the immersed sheet washeated to 75° C. for one hour. Then the sheet was removed from thesuspension, dried at 100° C. and washed with water to remove looselyattached TiO₂ particles. The finished sheet contained a specific loadingof about 310 mg TiO₂/m², as determined by the difference in weightobserved between dried samples before and after TiO₂ loading.

Example 2 Preparation of a Photocatalytic Oxidative Fe₂O₃-Coated Sheet

The procedure of example 1 was used, except that α-Fe₂O₃ powder wassubstituted for the TiO₂ powder. The finished sheet contained a specificloading of about 360 mg Fe₂O₃/m², as determined by the difference inweight observed between dried samples before and after Fe₂O₃ loading.

Example 3 Preparation of a Photocatalytic Oxidative Fe³⁺-Coated Sheet

A sheet of linear low density polyethylene (LLDPE) of 30 μm thickness,grafted with 1.5% of maleic anhydride, namely Fusabond 414 of Dupont,was taken as the polymeric carrier. The sheet was washed with water andthen immersed in an aqueous solution of FeCl₃ (Fluka) containing 5 gFeCl₃ per liter of solution. The solution with the immersed sheet washeated to 75° C. for one hour. Then the sheet was removed from thesolution, dried at 100° C. and washed with water. Fe³⁺ ions attached tothe finished sheet when leached out completely using HCl acid andanalyzed by calorimetric methods showed a loading of 3.05×10⁻³ molesequivalents of Fe³⁺ ions.

Example 4 Preparation of a Photocatalytic Oxidative ZnO-Coated Sheet

By the same procedure as in Example 1, but using ZnO instead of TiO₂, aphotooxidative ZnO-coated catalytic sheet was obtained.

Example 5 Photocatalytic Oxidative Degradation of Chlorophenols

A photooxidative catalytic sheet (size 12×4 cm) as obtained in example 1was used. The degradation reaction was run in a Pyrex glass reactor on0.5 mM aqueous solutions of 2-chlorophenol, 4-chlorophenol and2,4-dichlorophenol at a of pH 6. A 125 W medium pressure mercury arclamp (2.5×10¹⁵ photons/sec. in the wavelength range of 360 to 390 nm)was used as the light source, with the short wavelength part beingfiltered by the Pyrex wall of the reactor. The decrease in theconcentration of the chlorophenols was monitored by UV-VIS spectroscopyand by total organic carbon (TOC) analysis. The results are shown in the◯ curves of FIGS. 1 a, 1 b and 1 c.

Similar runs, except that the illumination was omitted, gave theexperimental ● curves of FIGS. 1 a, 1 b and 1 c, respectively.

Example 6 Photocatalytic Oxidative Degradation of 4-Chlorophenol

A photooxidative catalytic sheet (size 12×4 cm) as obtained in example 2was used. The degradation reaction was run under photo-Fenton conditionsin a Pyrex glass reactor on a 0.7 mM aqueous solution of 4-chlorophenolat pH 3 and with 0.01 M H₂O₂. A Hanau Suntest lamp (80 mW/cm² totalintensity, 1.6×10¹⁶ photons/sec. in the wavelength range of 350 to 560nm) was used as the light source, with the short wavelength part beingfiltered by the Pyrex wall of the reactor. The decrease in theconcentration of the 4-chlorophenol was monitored by UV-VIS spectroscopyand by total organic carbon (TOC) analysis. The result is shown in curvea) of FIG. 2 a.

A similar run, except that the illumination was omitted, gave theexperimental curve b) of FIG. 2 a).

Example 7 Photocatalytic Oxidative Degradation of Azo Dye Orange II

The same experimental setup as in example 6 was used, except that OrangeII in a concentration of 0.2 mM was substituted for the 4-chlorophenol.The result is shown in curve a) of FIG. 2 b).

A similar run, except that the illumination was omitted, gave theexperimental curve b) of FIG. 2 b).

Comparative Example 8 Photocatalytic Oxidative Degradation ofChlorophenols

The same experimental setup as in example 5 was used, except that theTiO₂ was used as a suspension of 75 mg/L in the reaction medium. Theresults are shown in the ★ curves of FIGS. 1 a, 1 b and 1 c,respectively.

Comparative Examples 9 and 10 Photocatalytic Oxidative Degradation of4-Chlorophenol

The same experimental setup as in example 6 was used, except that theFe₂O₃ was used as a suspension of 25 or 75 mg/L in the reaction medium.The results are shown in curves e) and f), respectively, of FIG. 2 a.

Comparative Examples 11 and 12 Photocatalytic Oxidative Degradation of4-Chlorophenol

The same experimental setup as in example 6 was used, except that theFe₂O₃ was used as a suspension of 25 or 75 mg/L and the H₂O₂concentration was reduced to 0.001 M. The results are shown in curves c)and d), respectively, of FIG. 2 a.

Comparative Examples 13 and 14 Photocatalytic Oxidative Degradation ofAzo Dye Orange II

The same experimental setup as in example 7 was used, except that theFe₂O₃ was used as a suspension of 25 or 75 mg/L. The results are shownin curves e) and f), respectively, of FIG. 2 b.

Comparative Examples 15 and 16 Photocatalytic Oxidative Degradation ofAzo Dye Orange II

The same experimental setup as in example 7 was used, except that theFe₂O₃ was used as a suspension of 25 or 75 mg/L and the H₂O₂concentration was reduced to 0.001 M. The results are shown in curves c)and d), respectively, of FIG. 2 b.

1. A catalytic body for heterogeneous photocatalytic oxidativedegradation of organic material comprising an organic polymer with apolymer backbone which forms a polymeric carrier for the catalytic body;a surface facing towards an environment of use, a carboxylic acidderivative having a β-carbon atom and selected from the group consistingof a carboxylic acid, a carboxylic ester, a carboxylic anhydride and anacyl halogenide, being connected by said β-carbon atom contained thereinto a carbon atom of said polymer backbone; and a metalcation(s)-containing photooxidation catalyst; wherein the photooxidationcatalyst is bonded to carboxylate moieties COO⁻ protruding from saidsurface and being obtained from said carboxylic acid derivative, whichbond to metal cation(s) contained in the photooxidation catalyst.
 2. Acatalytic body according to claim 1, wherein the polymer is selectedfrom the group consisting of polyethylene, linear low densitypolyethylene (LLDPE), polypropylene, polystyrene, polyester, polyamideand ethylene/vinyl acetate copolymer.
 3. A catalytic body according toclaim 2, wherein the photooxidation catalyst is bonded to carboxylatemoieties COO⁻ of a succinate and/or hemisuccinate which are connected tothe backbone of the organic polymer.
 4. A catalytic body according toclaim 3, wherein the polymer is LLDPE and the total amount of connectedsuccinate and/or hemisuccinate is 0.1 to 10 percent by weight based onLLDPE.
 5. A catalytic body according to claim 1, wherein thephotooxidation catalyst is selected from the group consisting of TiO₂,ZnO, Fe₂O₃, Fe³⁺ and mixtures thereof.
 6. A catalytic body according toclaim 1, wherein the photooxidation catalyst is a metal oxide which isdoped with an element selected from the group consisting of Li, Al, Nb,Ti, Si, P, In, Ga, Sb, and Cr or loaded with a metal selected from thegroup consisting of Pt, Pd, Ag, and Ni or with an oxide thereof.
 7. Aprocess for manufacture of a catalytic body for heterogeneousphotocatalytic oxidative degradation of organic material, comprising a)providing a bulk organic polymer with a polymer backbone and with acarboxylic acid derivative having a β-carbon atom and selected from thegroup consisting of a carboxylic acid, a carboxylic ester, a carboxylicanhydride and an acyl halogenide, being connected by said β-carbon atomcontained therein to a carbon atom of said backbone; and shaping saidbulk polymer into a body with a desired shape and surface(s) pointingtowards an environment of use, b) reacting carboxylate moieties COO⁻protruding from said surface(s) and being obtained by hydrolysis of saidcarboxylic acid derivative with a catalytically active photooxidativemetal cation, whereby the photooxidative metal cation(s) are bonded tosaid protruding surface carboxylate moieties —COO⁻.
 8. A process formanufacture of a catalytic body for heterogeneous photocatalyticoxidative degradation of organic material, comprising a) providing abulk organic polymer with a polymer backbone and with a carboxylic acidderivative having a β-carbon atom and selected from the group consistingof a carboxylic acid, a carboxylic ester, a carboxylic anhydride and anacyl halogenide, being connected by said β-carbon atom contained thereinto a carbon atom of said backbone; and shaping said bulk polymer into abody with a desired shape and surface(s) pointing towards an environmentof use, b) reacting said carboxylic acid derivative with a catalyticallyactive photooxidative metal oxide comprising surface hydroxyls, wherebythe photooxidative metal oxide is bonded by means of surface carboxylatemoieties —COO⁻ which protrude from said surface and which bond to metalcation(s) of the oxide.
 9. The process of claim 7, wherein the polymeris selected from the group consisting of polyethylene, linear lowdensity polyethylene (LLDPE), polypropylene, polystyrene, polyester,polyamide, and ethylene/vinyl acetate copolymer.
 10. The process ofclaim 9, wherein the photooxidation catalyst is bonded to carboxylatemoieties COO⁻ of a succinate and/or hemisuccinate which are connected tothe backbone of the organic polymer.
 11. A catalytic body for theheterogeneous photocatalytic oxidative degradation of organic material,obtained by the process of claim
 7. 12. Titanium dioxide bound to asuccinate which is connected by a β-carbon atom contained therein tolinear low-density polyethylene (LLDPE).
 13. A catalytic body accordingto claim 3, wherein the photooxidation catalyst is a metal oxide whichis doped with an element selected from the group consisting of Li, Al,Nb, Ti, Si, P, In, Ga, Sb, and Cr or loaded with a metal selected fromthe group consisting of Pt, Pd, Ag, and Ni or with an oxide thereof. 14.A process for the photocatalytic oxidative degradation of organicmaterial in a medium containing said organic material, whereby acatalytic body according to claim 1 is contacted with the medium suchthat the surface of the body facing the environment of use comes intocontact with the medium, and whereby the surface is illuminated in thepresence of molecular oxygen and/or hydrogen peroxide with light in awavelength and intensity appropriate to excite the photooxidativecatalyst.
 15. A catalytic body according to claim 2, wherein thephotooxidation catalyst is a metal oxide which is doped with an elementselected from the group consisting of Li, Al, Nb, Ti, Si, P, In, Ga, Sb,and Cr or loaded with a metal selected from the group consisting of Pt,Pd, Ag, and Ni or with an oxide thereof.
 16. A catalytic body accordingto claim 2, wherein the photooxidation catalyst is selected from thegroup consisting of TiO₂, ZnO, Fe₂O₃, Fe³⁺ and mixtues thereof.
 17. Acatalytic body according to claim 3, wherein the photooxidation catalystis selected from the group consisting of TiO₂, ZnO, Fe₂O₃, Fe³⁺ andmixtures thereof.